# ASTM E617-13

Designation: E617 − 13Standard Specification forLaboratory Weights and Precision Mass Standards1This standard is issued under the fixed designation E617; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (´) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers weights and mass standardsused in laboratories, specifically classes 000, 00, 0, 1, 2, 3, 4,5, 6 and 7. This specification replaces National Bureau ofStandards Circular 547, Section 1, which is out of print.1.2 This specification contains the principal physical char-acteristics and metrological requirements for weights that areused.1.2.1 For the verification of weighing instruments;1.2.2 For the calibration of weights of a lower class ofaccuracy; and1.2.3 With weighing instruments.1.3 Maximum Permissible Errors (formerly tolerances) anddesign restrictions for each class are described in order thatboth individual weights or sets of weights can be chosen forappropriate applications.1.4 The values stated in SI units are to be regarded asstandard.1.5 Weight manufacturers must be able to provide evidencethat all new weights comply with specifications in this standard(e.g., material, density, magnetism, surface finish, mass values,uncertainties). Statements of compliance by calibration labo-ratories during subsequent calibrations must meet the require-ments of ISO/IEC 17025, 5.10.4.2 and indicate on the calibra-tion report which sections have or have not been assessed.2. Referenced Documents2.1 ISO Standards:2ISO/IEC 17025 General Requirements for the Competenceof Testing and Calibration Laboratories (2005)2.2 NIST Standards:3NIST Handbook 143 State Weights and Measures Laborato-ries Program Handbook (2007)NIST SP 811 Guide for the Use of the International Systemof Unit (SI) 2008 EditionNIST SP 1038 The International System of Units (SI) –Conversion Factors for General Use (May 2006)NISTIR 5672 Advanced Mass Calibration and MeasurementAssurance Program for State Calibration Laboratories(2012)NISTIR 6969 Selected Laboratory and Measurement Prac-tices to Support Basic Mass Calibrations (2012)NIST Technical Note 1297 (1994) Guidelines for Evaluatingand Expressing the Uncertainty of NIST MeasurementResults2.3 OIML Standards:4OIML D 28 Conventional Value of the Result of Weighing inAir (2004)OIML R111–1e04 Weights of classes E1, E2, F1, F2, M1,M1–2, M2, M2–3 and M3 Part 1: Metrological andTechnical Requirements (2004)2.4 BIPM Standards:VIM: JCGM 200:2012 International Vocabulary of Metrolo-gy–Basic and General Concepts and Associated TermsGUM: JCGM 100:2008 Evaluation of MeasurementData–Guide to the Expression of Uncertainty in Measure-ment2.5 EURAMET Standards:EURAMET/cg-18/V. 3.0 Guidelines on the Calibration ofNon-Automatic Weighing Intruments (2011)2.6 Additional Reference Documents:CIPM-2007 Revised Formula for the Density of Moist Air,A. Picard, R. S. Davis, M. Glaser, and K. Fujii3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 accuracy class of weights—a class of weights thatmeets certain metrological requirements intended to keep theerrors within specified limits.3.1.2 balance—instument indicating apparent mass that issensitive to the following forces:1This specification is under the jurisdiction of ASTM Committee E41 onLaboratory Apparatusand is the direct responsibility of Subcommittee E41.06 onWeighing Devices.Current edition approved May 1, 2013. Published July 2013. Originally approvedin 1978. Last previous edition approved in 2008 as E617 – 97 (2008). DOI:10.1520/E0617-13.2Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.4Available from Organisation Internationale de Metrologie Legale, 11 RueTurgot, 75009 Paris, France.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Fg5 m·gForce due to gravityFb5 v·ρa·g 5mρρa·gAir buoyancy equal to the weight ofthe displaced air.Fz5 µoeeevsM 1 χ Hd≠ H≠ zdVVertical component of the magneticinteraction between the weight andthe balance or the environment, orboth.H and M are vectors; z is the vertical cartesian coordinate.If magnetic effects are negligible, i.e. the permanent magne-tization (M) of the weight and the magnetic susceptibility (χ)are sufficiently small, and the balance is calibrated with ref-erence weights of well-known mass, the balance can be usedto indicate the conventional mass, mc, of a body under con-ventionally chosen conditions.3.1.3 calibration (of weights)—the acts of determining themass difference between a standard of known mass value andan “unknown” test weight or set of weights, establishing themass value and conventional mass value of the “unknown,”and of determining a quantitative estimate of the uncertainty tobe assigned to the stated mass or conventional mass value ofthe “unknown,” or both, and providing metrological traceabil-ity to the “unknown.”3.1.3.1 calibration (generally)—set of operations thatestablish, under specified conditions, the relationship betweenvalues of quantities indicated by a measuring instrument ormeasuring system, or values represented by a material measureor a reference material, and the corresponding values realizedby standards.3.1.4 calibration certificate—certificate issued by calibra-tion laboratories to document the results of a calibration.3.1.5 conventional mass—conventional value of the resultof weighing in air, in accordance to International Recommen-dation OIML D 28. For a weight taken at 20°C, the conven-tional mass is the mass of a reference weight of a density of8000 kg/m3which it balances in air of density of 1.2 kg/m3.3.1.6 correction—mass values are traditionally expressed bytwo numbers, one being the nominal mass of the weight, andthe second being a correction. The mass of the weight is theassigned nominal value plus the assigned correction. Positivecorrections indicate that the weight embodies more mass thanis indicated by the assigned nominal value. Negative correc-tions indicate that the weight embodies less mass than isindicated by the assigned nominal value. The correction isequivalent to the “error.”3.1.7 international prototype kilogram—the platinum-iridium cylinder maintained at the International Bureau ofWeights and Measures (BIPM), at Sevres, France with aninternationally accepted defined mass of 1 kg.3.1.8 magnetism—effect that generates an attractive or re-pulsive force.3.1.8.1 (volume) magnetic susceptibility (χ)—measure of theability of a medium to modify a magnetic field. It is related tothe magnetic permeability (µ) by the relation: µ/µ0=1+χ. Thequantity µ/µ0is sometimes referred to as the relativepermeability, µr.3.1.8.2 (permanent) magnetization (M)—parameter thatspecifies a magnetic state of material bodies such as weights, inthe absense of an external magnetic field (most generally,magnetization is a vecotr whose magnitude and direction arenot necessarily constant within the material). The magnetiza-tion of a body generates an inhomogeneous magnetic field inspace and thus may produce magnetic forces on other materi-als.3.1.9 mass—physical quantity, which can be ascribed to anymaterial object and which gives a measure of its quantity ofmatter. The unit of mass is the kilogram.3.1.10 maximum permissible errors—the maximum amountby which the sum of the conventional mass of the weight, itsdeviation from nominal value and its associated uncertainty isallowed to deviate from the assigned nominal value.3.1.11 metrological traceability—property of a measure-ment result whereby the result can be related to a referencethrough a documented unbroken chain of calibrations, eachcontributing to the measurement uncertainty. Metrologicaltraceability requires an established calibration hierarchy. Ele-ments for confirming metrological traceability to be an unbro-ken chain to an international measurement standard or anational measurement standard (IPK or NPS), shall include adocumented measurement uncertainty, a documented measure-ment procedure, accredited technical competence, metrologicaltraceability to the SI, and established calibration intervals (seecurrent VIM: JCGM 200).3.1.12 reference standard—a standard, generally of thehighest metrological quality available at a given location, fromwhich measurements made at that location are derived.3.1.13 roughness parameter or R-parameter (Raor Rz)—parameter that describes the assessed roughness profile of asample. The letter R is indicative of the type of assessedprofile, in this case R for roughness profile. The assessedprofile of a sample can be in terms of different profile types: aroughness profile or R-parameter, primary profile orP-parameter, a waviness profile or W-parameter.3.1.14 set of weights—a series of weights, usually presentedin a case so arranged to make possible any weighing of allloads between the mass of the weight with the smallest nominalvalue and the sum of the masses of all weights of the serieswith a progression in which the mass of the smallest nominalvalue weight constitutes the smallest step of the series.3.1.15 temperature (t)—in degrees Celsius, is related to theabsolute thermodynamic temperature scale, called the Kelvinscale, by t=T– 273.15 K.3.1.16 test weight (mt)—weight that is to be tested accordingto this standard.3.1.17 tolerance test—verification that the conventionalmass of the weights and their corresponding uncertainties astested are correct within the maximum permissible errors of therespective weight class.3.1.18 uncertainty—non-negative parameter characterizingthe dispersion of the quantity values being attributed to ameasurand, based on the information used.E617 − 1323.1.19 units—the units used are: (1) for mass, the milligram(mg), the gram (g) and the kilogram (kg); (2) for density, thekilogram per cubic meter (kg m–3).3.1.20 U.S. National prototype standard—platinum-iridiumkilogram identified as K20, maintained at the National Instituteof Standards and Technology, with value assigned relative tothe International Prototype Kilogram provides the UnitedStates access to the mass unit.3.1.21 weight—material measure of mass, regulated in re-gard to its physical and metrological characteristics: shape,dimensions, material, surface quality, nominal value, density,magnetic properties and maximum permissible error.NOTE 1—The term “weight” is also used as the physical quantity of thegravitational force of a body. From the context it is usually clear in whichsense the term is used. If the sense is not clear, one may use the words“weight force” or “weight piece,” depending on its meaning.3.2 Symbols:Symbol Unit DefinitionA – represents weighing the referenceweight in a weighing cycleB – represents weighing the test weight ina weighing cycleC – correction factor for air buoyancyD kg difference of balance readingsbetween minimum and maximumvalues from eccentricity testd kg scale intervald1m estimated distance between centers ofweights during loadingd2m estimated distance from the center ofthe load receptor to one of the cornersFbN air buoyancy equal to the weight of thedisplaced airFgN gravitational forceFzN magnetic force between a masscomparator and a weight in the verticalor z-directiong ms–2gravitational accelerationH Am–1magnetizing field strengthhr % relative humidityI kg indication of the weighing instruments(scale division)∆I kg indication difference of the balance,where ∆I = It–Ir∆I1kg indication difference using anautomatic exchange mechanism withweights in first position∆I2kg indication difference using anautomatic exchange mechanism withweights in reversed position∆Iskg change in indication of balance due tosensitivity weighti – subscript used as an index insummationsj – subscript for number of test weights ornumber of series of measurementsk – coverage factor, typically 2 or 3M Am–1permanent magnetization (see alsoµ0M)m kg mass of a rigid body (weight)∆m kg mass difference, usually between testand reference weightδm kg maximum permissible error on theweightsm0kg mass, nominal value of the weight(e.g. 1 kg)mckg conventional mass of the weight∆mckg conventional mass difference betweentest weight and reference weightSymbol Unit Definition∆mc¯kg average conventional mass differencebetween test weight and referenceweightmcrkg conventional mass of the referenceweightmctkg conventional mass of the test weightmskg mass of the sensitivity weightmtkg mass of the test weightn – subscript for number of measurementsequencesp Pa barometric pressureRaµm mean height of roughness profile (R-parameter)Rzµm maximum height of roughness profile(R-parameter)r – subscript for reference weights – subscript for sensitivity weights kg standard deviations2kg2varianceT K thermodynamic temperature using theInternational Temperature Scale of1990 (ITS-90)∆T* °C initial difference between weight tem-perature and laboratory temperaturet – subscript for test weightt °C temperature in degrees Celsius, wheret = T– 273.15 KU kg uncertainty, expanded uncertaintyu kg uncertainty, standard uncertaintyubkg uncertainty of air buoyancy correctionubakg uncertainty of the balanceuckg combined standard uncertaintyudkg uncertainty due to the display resolu-tion of a digital balanceuEkg uncertainty due to eccentricityuFkg m–3uncertainty of the formula used to cal-culate air densityuhr% uncertainty in relative humidityuinstkg uncertainty due to instability of the ref-erence weightumakg uncertainty due to magnetismupPa uncertainty in barometric pressureuskg uncertainty due to the sensitivity of thebalanceut°C uncertainty in temperatureuwkg uncertainty due to the weighing pro-cessV m3volume of a solid body (weight)z m vertical cartesian coordinateµNA–2magnetic permeabilityµ0NA–2magnetic constant (magnetic perme-ability of vacuum), µ0=4π ×10–7NA–2µ0M T magnetic polarizationµr– relative magnetic permeability (µ/µ0)veff– effective degrees of freedomρ kg m–3mass of a rigid body (weight)ρ0kg m–3density of air as a reference valueequal to 1.2 kg m–3ρakg m–3density of moist airρalkg m–3density of moist air during the last(previous) calibration of the referenceweightρrkg m–3density of a reference weight withmass mrρtkg m–3density of the weight being testedχ – magnetic susceptibility4. Maximum Permissible Errors4.1 For each weight, the expanded uncertainty U at approxi-mately 95 % confidence (See Section 9) of the conventionalmass shall be less than or equal to one-third of the maximumpermissible error given in Table 1 as defined in Section 9.E617 − 133TABLE 1 Maximum Permissible ErrorsNOTE 1—Maximum Permissible Errors are reported in SI units, typically mi